Tag: original

structure

Shock metamorphism & shatter cones

itssedimentary

Above: A shatter cone in dolomite from the Kentland, Indiana impact structure (Specimen from Lawrence University.) Meteorite impacts are pretty amazing things. An impact crater forms instantaneously on a human time scale, with the shock wave from the impact propagation through the target rock in the following stages: contact and compression, crater excavation, and crater modification. Some… Continue reading Shock metamorphism & shatter cones

mass extinction monday, paleobiology, paleoclimate

Mass Extinction Monday | END-ORDOVICIAN (440 Ma)

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Severity: 2nd worst Cause: Some type of C cycle disturbance, not well constrained Climate: Abrupt ice age followed by rapid warming Aftermath: Cambrian organisms (e.g. trilobites) decimated During the End-Ordovician mass extinction, 25% of known marine families and 60% of marine genera were wiped out. Warm-water invertebrates were the hardest hit, as the event was… Continue reading Mass Extinction Monday | END-ORDOVICIAN (440 Ma)

mass extinction monday, paleobiology

Mass Extinction Monday!

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Starting a new feature here! Every Monday, they’ll be a little overview of each of the five big mass extinctions, To start off, we’re going to do a bit of a general overview. Around 99% of all species that have ever lived on Earth are extinct.1 However, this extinction rate is far from constant, as organisms… Continue reading Mass Extinction Monday!

geochronology

~4.55 BILLION YEARS – TO SCALE!

itssedimentary

Typically when you look at a geologic time scale, the Precambrian is all scrunched up, so even though it accounts for about 80% of Earth’s history, you forget how significant it is in the whole scheme of things. Putting the time scale into perspective like this just makes me marvel even more at human existence…… Continue reading ~4.55 BILLION YEARS – TO SCALE!